I got this to work using PPP Widget. It requires a rooted nexus 7 and a usb otg cable. Unlike BlueVPN, it's not wireless, but it gives full internet access on the tablet and it does so at very good speeds.

Steps:

Download PPP Widget from the play store and add the widget to a homescreen (grant superuser access when prompted).
Select "Configure" on the widget.
- Fill in Access Point Name (I just entered a blank space here).
- Disable automatic device detection.
Connect N9 with usb otg cable.
- Choose "Sync and connect" option on N9.
Select the PPP icon and choose your N9 from the list.
Hit Connect.

The widget manages the wifi connection so I didn't have to turn off wifi on the nexus to get this to work. I have yet to find an internet enabled app that can't connect to the net.

Bonus: not only does the n9 charge while connected to the nexus 7, the wifi hotspot app can be used simultaneously for other devices.